Nowadays, with the widespread use of cellphones and other battery-powered electronic devices, battery fuel gauging is paid with more and more attention by developers of electronic devices. As is shown in FIG. 1, which is a structural diagram of a battery fuel gauging system in the prior art. Today's battery fuel gauging system generally comprises a microprocessor module 11, a current sensor module 12 and a current-sense resistor Rs. Due to the fact that the current-sense resistor Rs must be set inside the battery and the microprocessor module 11 is directly powered by the battery, the battery fuel gauging system can only be located inside the battery. The microprocessor module 11 can keep data exchange via the universal communication interface with the processor of the electronic device. When the battery fuel gauging system is working properly, it needs to continuously collect a terminal voltage between the two terminals of the current-sense resistor Rs, and calculate the real-time current in order to get the remaining charge in the battery. When the entire electronic device is turned into a sleep mode, a standby mode or a ultra-low-power mode, the battery fuel gauging system will still collect the terminal voltage and utilize the SOC-OCV relevance, i.e., the relevance between state of charge and open-circuit voltage in order to correct the charge estimation offset.
While the prior art has at least the following disadvantages:
1. The battery fuel gauging system in the prior art has relatively high power consumption. Specifically, when the system is working, it needs to monitor in real time the magnitude of the current; otherwise the charge amount cannot be accurately accumulated. Thus, the sampling system must be kept in a real-time working condition, in other words, the sampling module must be working in a continuously active state, and this leads to the consequence that the system's overall power will always remain at a relatively high level and it is impossible for the system to actively adjust its working state according to load conditions.
2. When the system is working, it cannot autonomously eliminate the inevitable long-term charge offset in current sampling, thus it cannot automatically correct the deviation under a normal working state. Since the current sense resistor itself has limited precision, the accumulated error caused thereby can only be corrected when the system is turned into the sleep mode, the standby mode or the ultra-low-power mode, by utilizing an open-circuit voltage acquired from voltage sampling to perform the charge correction. When the system is in a continuous working state or in a condition of repeatedly charging or discharging, then it cannot autonomously monitor the system error, thus affecting the precision when the system is working continuously or is being repeatedly charging or discharging. When the system is in the sleep mode, the standby mode or the ultra-low-power mode, the charge correction is generally performed in an abrupt manner, i.e., the charge update is performed immediately after the sampling is completed, thus, the display of the charge level would change abruptly when the electronic device is switched on or off.
3. The battery fuel gauging system in the prior art can only be set inside the battery.